Approximately 20-40% of the population experiences elevated depressive symptoms (Kubik et al., 2003). Despite recent research suggesting that overall population mortality would be reduced by 6.5% if the effects of subthreshold depression could be blocked completely, the majority of individuals with elevated depressive symptoms never receive evidence-based treatment (Cuijpers et al., 2013). Elevated depressive symptoms are most frequently reported to primary care physicians (PCPs; Mitchell et al., 2009), who lack evidence-based resources for the treatment of subthreshold depression. This lack of evidence-based resources leads to a number of negative outcomes for patients including: 1) the majority not receiving appropriate treatment (Kessler et al., 2005), 2) a decreased likelihood of reporting depressive symptoms again in the future (Bell et al., 2011), and 3) heightened mortality risk (Cuijpers et al., 2004). As the most likely initial contact for patients with elevated depressive symptoms, PCPs are in a unique position to provide evidence-based interventions (McDowell et al., 2011). In light of factors that deter use of evidence-based strategies by PCPs, including the necessity of additional training to support implementation and/or excessive costs to patients, mobile technologies such as mobile apps offer an ideal strategy to meet widespread treatment needs. However, there are currently no mobile apps for depressive symptoms available to PCPs that are both evidence-based and straightforward enough to be recommended to their patients. One treatment for elevated depressive symptoms that is particularly amenable to a mobile platform and could easily be recommended by PCPs is brief Behavioral Activation (brief BA; Lejuez et al., 2011). Across studies, brief BA has demonstrated effectiveness for reducing depressive symptoms among individuals with elevated depressive symptoms (Gawrysiak et al., 2009; Hopko et al., 2003; Reynolds et al., 2011). Despite this clear fit between brief BA, mobile platforms, and PCPs, such a tool has yet to be developed. The purpose of the proposed project is to customize BA for a mobile platform by creating a BA mobile application (Behavioral Apptivation) to be marketed to individuals with elevated depressive symptoms through their PCPs in order to address the currently unmet needs of PCPs and their patients with elevated depressive symptoms. We expect that via product development, acceptability and feasibility testing, and refinement consistent with the STTR Phase I funding mechanism, we will create a marketable product for which we will pursue larger scale clinical testing in an STTR Phase II study.